This invention relates to structures for providing a sheet of material or a box with a detachable surface area bearing a coupon or the like.
Detachable coupons and the like have found extensive use commercially, particularly in the direct mail industry and in retail sales of packaged goods. In the direct mail industry, for example, it is often desirable to provide sheets of printed matter with information areas which are meant to be detached by the recipients and returned to the sender, the areas typically bearing coupons entitling the recipients to discounts on particular items. In the case of packaged goods, boxes often have detachable information areas, typically bearing proof-of-purchase seals and coupons which may be accumulated for redemption of a premium offer.
The methods used for separating the information areas from the sheets or boxes have heretofore been limited to the cumbersome procedures of tearing the sheet or box along perforations or cutting through the thickness of the sheet or box with scissors or a knife edge. These techniques are subject to several disadvantages. For example, the sheet or box may fail to tear precisely at the perforations, possibly resulting in tearing the information area itself. The use of scissors to remove the information area is awkward and may require that a large area of the box be cut out and trimmed to size. Using a knife or razor blade to remove the information area, although less cumbersome than using scissors, presents the danger of accidental injury. Moreover, all these methods produce an opening in the sheet or box, with the result that the structural integrity of the sheet or box is reduced. More importantly, if the box contains perishables such as food, removal of the area before the box has been emptied may cause spoilage or contamination of the contents. Also, because the detached area has the same thickness as the sheet or box from which it is detached, detached areas of this type are bulky and therefore inconvenient and costly to mail.
Container structures having information areas thereon which may be manually detached without the use of scissors or a knife and which do not produce an opening in the container have been proposed in the prior art. See, for example, U.S. Pat. No. 2,142,470 to Claff and U.S. Pat. No. 3,110,121 to Corrinet. These container structures typically comprise a paper sheet and a boxboard sheet laminated together by an adhesive, the paper sheet having lines of weakness therein defining a detachable area of the sheet. The adhesive is made ineffective as to the defined area for preventing the area from adhering to the underlying boxboard sheet, thereby enabling the defined area of the paper layer to be detached from the container by tearing that layer along the lines of weakness.
As compared with boxes manufactured from a single sheet of material such as paperboard, as is presently a standard commercial practice, the multi-layer structures of the prior art are commercially disadvantageous because of the cost and inconvenience of providing and laminating two layers of material and because special apparatus is necessary for laminating the layers by means of an adhesive without permitting the detachable area to adhere to the underlying layer.